Users frequently perform Internet search queries for products being offered for sale. As part of understanding the user intent of shopping-related search queries, it is important for product search engines to understand various aspects of product categories. For example, most products are associated with a brand. As another example, most digital cameras have a specified number of megapixels. An important product aspect that can change over time, sometimes rapidly, is the product line. Companies introduce new product lines and retire old ones quite frequently. There is a need in the art to automatically detect terms designating product lines from within product queries provided by search users. There is a further need to associate the detected product line terms with their corresponding brands to keep up with recognizing new product lines and retiring old product lines soon after changes occur.